#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
using namespace std;
using std::cout;
using std::cin;
using std::endl;
using ll=long long;
using ld=long double;
ll ILL=2167167167167167167;
const int INF=2100000000;
const ll mod=998244353;
#define rep(i,a) for (ll i=0;i<a;i++)
#define all(p) p.begin(),p.end()
template<class T> using _pq = priority_queue<T, vector<T>, greater<T>>;
template<class T> ll LB(vector<T> &v,T a){return lower_bound(v.begin(),v.end(),a)-v.begin();}
template<class T> ll UB(vector<T> &v,T a){return upper_bound(v.begin(),v.end(),a)-v.begin();}
template<class T> bool chmin(T &a,const T &b){if(a>b){a=b;return 1;}else return 0;}
template<class T> bool chmax(T &a,const T &b){if(a<b){a=b;return 1;}else return 0;}
template<class T> void So(vector<T> &v) {sort(v.begin(),v.end());}
template<class T> void Sore(vector<T> &v) {sort(v.begin(),v.end(),[](T x,T y){return x>y;});}
void yneos(bool a){if(a) cout<<"Yes\n"; else cout<<"No\n";}
template<class T> void vec_out(vector<T> &p){for(int i=0;i<(int)(p.size());i++){if(i) cout<<" ";cout<<p[i];}cout<<"\n";}
template<class T> T min(vector<T> &a){assert(!a.empty());T ans=a[0];for(auto &x:a) chmin(ans,x);return ans;}
template<class T> T max(vector<T> &a){assert(!a.empty());T ans=a[0];for(auto &x:a) chmax(ans,x);return ans;}
template<class T> T sum(vector<T> &a){assert(!a.empty());T ans=a[0]-a[0];for(auto &x:a) ans+=x;return ans;}



void solve();
// oddloop
int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	
	int t=1;
	//cin>>t;
	rep(i,t) solve();
}

void solve(){
	ll N;
	cin>>N;
	vector<ll> fact(N+1,1);
	rep(i,N) fact[i+1]=(fact[i]*2ll)%mod;
	string S,T;
	cin>>S>>T;
	if(S.size()>T.size()) swap(S,T);
	int L=0;
	while(L<(int)S.size()&&S[L]==T[L]) L++;
	ll ans=0;
	auto f=[&](int dan)->ll{
		return ((fact[N]-fact[N-dan])*(fact[N-dan]-1))%mod;
	};
	for(int i=1;i<N;i++){
		ans+=(fact[i]*f(i))%mod;
		ans%=mod;
	}
	if(S==T){
		cout<<(ans+mod)%mod<<"\n";
		return;
	}
	for(int i=L;i<(int)(T.size());i++) ans-=f(i);
	for(int i=L;i<(int)(S.size());i++) ans-=f(i);
	ans=(ans+mod)%mod;
	vector<ll> p,q;
	if(L==(int)S.size()){
		p.push_back(fact[N]-fact[N-L]);
		for(int i=L+1;i<(int)(T.size());i++){
			p.push_back(fact[N-i]);
		}
		p.push_back(fact[N+1-(int)(T.size())]-1);
	}else{
		p.push_back(fact[N]-fact[N+1-L]+1);
		for(int i=L+1;i<(int)(S.size());i++){
			p.push_back(fact[N-i]);
		}
		p.push_back(fact[N+1-(int)(S.size())]-1);
		for(int i=L+1;i<(int)(T.size());i++){
			q.push_back(fact[N-i]);
		}
		p.push_back(fact[N+1-(int)(T.size())]-1);
		reverse(all(q));
		for(auto x:q) p.push_back(x);
	}
	ans=(ans*2ll)%mod;
	ll len=p.size();
	ll tmp=0,diff=0;
	rep(i,len){
		tmp=(tmp+min(i,len-i)*p[i])%mod;
		if(i!=0&&i<=len/2) diff-=p[i];
		if(i==0||(len+1)/2<i) diff+=p[i];
	}
	rep(i,len){
		ans=(ans+(tmp*p[i])%mod)%mod;
		tmp=(tmp+diff)%mod;
		diff+=(p[(i+1)%len]*2ll);
		diff-=p[(len/2+1+i)%len];
		diff-=p[((len+1)/2+1+i)%len];
		diff%=mod;
	}
	ans=(ans*((mod+2)/2))%mod;
	cout<<(ans%mod+mod)%mod<<"\n";
}